On small devices like smartphones and tablet PCs, the space for the “keyboard” presented on the display touch panel of the graphical user interface is limited and typically much smaller than in regular keyboards. Furthermore, because of the nature of the display touch panel, ten-finger typing is not possible.
In many display touch panels, the number of keys is reduced to a minimum. For example, in many such keyboard displays, there is only one shift key, no keylock key, no number keys, and no special character keys. Those characters can only be accessed via extra input modes reachable via a shift key, which display a second “keyboard.” Thus, it is always required to make two consecutive keystrokes to access upper keys, numbers, special characters or additional control functions.